Silica–Polystyrene Hybrid Core/Shell Microparticles of Rhodium–Chiral Diene Complexes as Catalysts for Asymmetric 1,4-Addition Reactions

Heterogeneous catalysts for fine chemical synthesis play a crucial role in establishing an efficient chemical process. Immobilization of homogeneous catalysts is an important method for the preparation of heterogeneous catalysts; however, it is often accompanied by a loss of catalytic activity due to limited mass transport in the support matrix. Here, we have designed core/shell type polystyrene shell supports on silica with low degrees of cross-linking to improve accessibility to reaction sites. It was found that rhodium–chiral diene complexes on core/shell particles showed higher catalytic activity in comparison those on conventional supports and even better catalytic activity than the corresponding homogeneous catalyst in asymmetric 1,4-addition reactions. Our results may provide a general strategy to obtain many other heterogeneous catalysts with high activities.